High-speed semiconductor laser diode driving circuit system and driving method

Abstract

The invention belongs to the technical field of semiconductor laser diodes, and particularly discloses a high-speed semiconductor laser diode driving circuit system and method, and the system comprises an FPGA (Field Programmable Gate Array), an EEPROM (Electrically Erasable Programmable Read-Only Memory), an internal and external trigger signal selection circuit module, a narrow pulse signal generation circuit module, a constant-current compensation circuit module, an LD (Laser Diode) driving gain adjustment module and a temperature control module. The output power of the high-speed semiconductor laser diode is stable, the laser diode can work in a stable temperature environment, multiple modes of internal trigger / external trigger and continuous / pulse can be switched, the function that the pulse repetition frequency and the pulse width are adjustable is achieved, operation is easy, use is flexible, and the high-speed semiconductor laser diode can be suitable for multiple working scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor laser diodes, and in particular to a high-speed semiconductor laser diode driving circuit system and a driving method. Background Art

[0002] In recent years, with the rapid expansion of semiconductor laser applications, it has been widely used in optical communications, laser detection, optical storage, optical radar and laser processing due to its advantages of small size, long life, high efficiency, fast modulation and integration. In many fields, especially in the field of optical communications, the transmission rate, anti-interference ability and transmission distance all depend on the quality of the laser pulse emitted by the semiconductor laser. The light pulse emitted by the semiconductor laser is directly modulated by the electric pulse generated by the semiconductor laser diode drive circuit, so the determining factor of the laser pulse quality lies in the quality of the electric pulse. Therefore, the research on semiconductor laser drive circuits is a key technology in optical communications and laser detection.

[0003] For example, a laser driving circuit (publication number: CN108767655B, publication date: 2024-04-26) includes a current conversion unit, an amplifier, a feedback unit, a detector, a digital potentiometer, a processor and a power supply. The current conversion unit is configured to convert a back current signal into a voltage signal; the amplifier is configured to further amplify the voltage signal converted by the current conversion unit and output the amplified voltage signal; the feedback unit is configured to convert the amplified voltage signal into a current signal; the detector is configured to detect the voltage signal of the current conversion unit and transmit the voltage signal to the sampling port of the processor; the digital potentiometer is configured as an adjustable resistor for driving the circuit resistance control. Compared with the prior art, this design achieves stable laser light emission.

[0004] However, the driving circuit cannot switch between external trigger mode and internal trigger mode and between pulse light and continuous light working modes. It is also unable to accurately change the pulse width and repetition frequency of the laser during operation. Therefore, the laser cannot be used in application scenarios of high-precision and high-speed laser pulses, nor can it be used in application scenarios of continuous laser irradiation, thus limiting the application scope of the semiconductor laser diode driving system.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0006] The purpose of the present invention is to solve the technical problems existing in the background technology. To this end, a high-speed semiconductor laser diode driving circuit system and a driving method are provided.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A high-speed semiconductor laser diode drive circuit system, including FPGA, EEPROM, internal and external trigger signal selection circuit module, narrow pulse signal generation circuit module, constant current compensation circuit module, LD drive gain adjustment module and temperature control module;

[0009] The FPGA is electrically connected to the EEPROM, the internal and external trigger signal selection circuit module, the narrow pulse signal generation circuit module, the constant current compensation circuit module and the LD drive gain adjustment module respectively;

[0010] The LD drive gain adjustment module, the constant current compensation circuit module and the temperature control module are all electrically connected to the laser diode;

[0011] The internal and external trigger signal selection circuit module is used to select the external or internal input trigger signal to adjust the working mode of the system;

[0012] The narrow pulse signal generating circuit module is used to convert the trigger signal into a pulse signal;

[0013] The temperature control module monitors and controls the operating temperature of the laser diode, so that the laser diode operates at a constant temperature.

[0014] The following is a technical solution further defined by the driving circuit system in the present invention, wherein the internal and external trigger signal selection circuit module comprises a comparator and a selector electrically connected in sequence;

[0015] The comparator is used to convert the external input signal into a trigger signal;

[0016] The selector is electrically connected to the FPGA, and the FPGA generates a signal and sends it to the selection input terminal and the differential input terminal of the selector;

[0017] When the FPGA sends a low-level signal to the selection input terminal of the selector, the internal and external trigger signal selection circuit module selects the external input signal, and the system is in external trigger mode at this time;

[0018] When the FPGA sends a high-level signal to the selection input terminal of the selector, the internal and external trigger signal selection circuit module selects the internal input signal generated by the FPGA. At this time, the system is in internal trigger mode.

[0019] The following is a technical solution further defined by the driving circuit system in the present invention, wherein the narrow pulse signal generating circuit module comprises a high-speed fan-out buffer, a delay chip, a high-speed logic gate chip and a high-speed comparator which are electrically connected in sequence;

[0020] The high-speed fan-out buffer, the delay chip, the high-speed logic gate chip and the high-speed comparator are DC-coupled in sequence;

[0021] The high-speed fan-out buffer is used to divide an input trigger signal into four electrical signals with the same amplitude, one of which is output as a synchronization signal and two are output to the delay chip;

[0022] The delay chip is used to set different delay values ​​for the two input signals and output them to the high-speed logic chip;

[0023] The high-speed logic gate chip is used to set logic operations for the two input signals respectively;

[0024] The high-speed comparator is used to eliminate noise in the electrical pulse signal and convert the signal output by the high-speed logic gate chip into an input signal for the driver chip;

[0025] The pulse signal after noise filtering is sent to the LD drive gain adjustment module.

[0026] The following is a technical solution further defined by the driving circuit system in the present invention, wherein the LD driving gain adjustment module includes a digital-to-analog conversion chip and a driving chip electrically connected;

[0027] The digital-to-analog conversion chip is electrically connected to the FPGA, and the digital-to-analog conversion chip adjusts the input reference voltage to control the modulation current of the driving chip;

[0028] The driving chip converts the signal after the logic operation into a radio frequency driving signal and outputs it to the laser diode.

[0029] The following is a technical solution further defined by the driving circuit system in the present invention. The temperature control module makes the laser diode work at a constant temperature according to a preset operating temperature value of the laser diode and by controlling the TEC cooling or heating in the laser diode.

[0030] The following is a technical solution further defined by the driving circuit system in the present invention, which also includes a host computer, which is electrically connected to the FPGA, and in which the electrical pulse width, working mode, gain voltage and trigger mode are set.

[0031] A laser diode driving method based on the above-mentioned high-speed semiconductor laser diode driving circuit system comprises:

[0032] Select working mode: The host computer sends instructions to the FPGA, and the FPGA controls the working mode of the system. The working modes include pulse mode and continuous mode.

[0033] Output RF drive signal:

[0034] When in pulse mode, the trigger signal after passing through the internal and external trigger signal selection circuit module is sent to the narrow pulse signal generation circuit module, the narrow pulse signal generation circuit module converts the trigger signal into a pulse signal and sends it to the LD drive gain adjustment module, the LD drive gain adjustment module converts the input signal into a drive signal of the laser diode to drive the operation of the laser diode;

[0035] When in continuous mode, the FPGA controls the constant current compensation circuit module to directly modulate the laser diode to keep the output optical power of the laser diode constant;

[0036] Temperature control: The temperature control module controls the temperature of the laser diode, so that the laser diode works at a constant temperature to ensure the stability of its optical power and wavelength;

[0037] Constant current compensation: The constant current compensation circuit module controls the compensation current to make the laser diode output a constant current.

[0038] Compared with the prior art, the present invention has the following technical effects:

[0039] The high-speed semiconductor laser diode in the present invention has stable output power, can make the laser diode work in a stable temperature environment, and can switch between internal triggering / external triggering, continuous / pulse modes, realizes the functions of adjustable pulse repetition frequency and pulse width, is simple to operate, flexible to use, and can be applied to a variety of working scenarios.

[0040] The present invention is further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 It is a system connection block diagram of the present invention;

[0043] Figure 2 It is a circuit connection schematic diagram of the present invention.

[0044] Figure 3 It is a circuit connection diagram of the temperature control module in the present invention. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0046] like Figure 1-3 As shown, this embodiment provides a high-speed semiconductor laser diode drive circuit system, which mainly includes FPGA, EEPROM, internal and external trigger signal selection circuit module, narrow pulse signal generation circuit module, constant current compensation circuit module, LD drive gain adjustment module and temperature control module. Among them, FPGA (Field-Programmable Gate Array) is a field programmable gate array; EEPROM (Electrically Erasable Programmable read only memory) refers to an electrically erasable programmable read-only memory, which is a storage chip in which data is not lost after power failure. FPGA is electrically connected to EEPROM, internal and external trigger signal selection circuit module, narrow pulse signal generation circuit module, constant current compensation circuit module and LD drive gain adjustment module respectively. The LD drive gain adjustment module, constant current compensation circuit module and temperature control module are all electrically connected to the laser diode.

[0047] EEPROM is connected to FPGA through IIC, which enables the system to store multiple modes and data after power failure. The constant current compensation circuit module controls the size of the compensation current so that the laser diode outputs a constant current and maintains its power stability. The temperature control module monitors and controls the operating temperature of the laser diode so that the laser diode works at a constant temperature and maintains the stability of the wavelength and output power. The internal and external trigger signal selection circuit module is used to select the external or internal input trigger signal so that the system's operating mode can be switched between the internal trigger mode and the external trigger mode. The narrow pulse signal generation circuit module is used to convert the trigger signal into a pulse signal.

[0048] The internal and external trigger signal selection circuit module includes a comparator (also called a high-speed comparator chip) and a selector (also called a selector chip) that are electrically connected in sequence. When in the external trigger mode, the comparator converts the external input signal into a trigger signal that meets the requirements, and the selector is used to select the external or internal input trigger signal so that the system's working mode can be flexibly changed. The selector is electrically connected to the FPGA, and the FPGA generates a signal and sends it to the selection input terminal and the differential input terminal of the selector. When the FPGA sends a low-level signal to the selection input terminal of the selector, the internal and external trigger signal selection circuit module selects the external input signal, and the system is in the external trigger mode. When the FPGA sends a high-level signal to the selection input terminal of the selector, the internal and external trigger signal selection circuit module selects the internal input signal generated by the FPGA, and the system is in the internal trigger mode. The trigger signal output by the internal and external trigger signal selection circuit module is sent to the narrow pulse signal generation circuit module for further processing.

[0049] The narrow pulse signal generating circuit modules all use high-speed chips, specifically including high-speed fan-out buffers, delay chips, high-speed logic gate chips and high-speed comparators that are electrically connected in sequence. The high-speed fan-out buffer, delay chip, high-speed logic gate chip and high-speed comparator are DC coupled in sequence. The high-speed fan-out buffer divides the input trigger signal into four electrical signals with the same amplitude, one of which is output as a synchronization signal, and two are output to the delay chip, which not only ensures that the original input signal is not deformed due to the load, but also ensures that the outputs of each channel are independent of each other and do not affect each other. The delay chip is used to set different delay values ​​for the two input signals and output them to the high-speed logic chip. The high-speed logic gate chip is used to set logical operations for the two input signals to obtain electrical pulse signals. The high-speed comparator is used to eliminate noise in the electrical pulse signal and convert the signal output by the high-speed logic gate chip into the input signal of the driver chip. The pulse signal after noise filtering is sent to the LD drive gain adjustment module.

[0050] The LD drive gain adjustment module includes an electrically connected digital-to-analog conversion chip and a driver chip. The digital-to-analog conversion chip is electrically connected to the FPGA via SPI. The digital-to-analog conversion chip adjusts the input reference voltage (converts the digital signal sent by the FPGA into the required analog signal to control its output voltage) to control the modulation current of the high-speed driver chip (the high-speed driver chip sets the modulation current of the high-speed driver chip according to the voltage output by the digital-to-analog conversion chip). The high-speed driver chip converts the signal after the logic operation into a radio frequency drive signal and outputs it to the laser diode (that is, the high-speed driver chip converts the pulse signal generated by the narrow pulse signal generation circuit module into a radio frequency drive signal and modulates it onto the laser diode).

[0051] The temperature control module controls the TEC cooling or heating in the laser diode according to the preset working temperature value of the laser diode to make the laser diode work at a constant temperature. The temperature control module includes an instrument amplifier and a high-efficiency thermoelectric cooling controller chip. The temperature control module uses a negative feedback closed-loop control system for adjustment. In order to achieve a temperature accuracy of 0.01°C, the circuit uses a two-stage amplifier circuit. The first stage uses a zero-drift instrument amplifier, and the second stage is the error amplifier EA built into the high-efficiency thermoelectric cooling controller chip. The resistor divider is used to directly set the temperature value for normal operation of the laser. The voltage at the thermistor is compared with the given voltage value. The error value obtained is amplified by the instrument amplifier to control the duty cycle of the PWM comparator output voltage, thereby controlling the conduction time on both sides of the full-bridge circuit to control the direction of the current and the voltage on the TEC to achieve the effect of controlling the temperature of the laser diode. A network composed of resistors and capacitors is connected between the reverse input and output ends of the error amplifier EA of the high-efficiency thermoelectric cooling controller chip to compensate the loop. The full-bridge circuit uses complementary N / P channel MOS field effect transistors, which should have ultra-low on-resistance and switching loss, which can significantly improve the working efficiency of the circuit.

[0052] The system also includes a host computer, which is electrically connected to the FPGA. The electrical pulse width, working mode, gain voltage, trigger mode, laser output power, and pulse repetition frequency value of the circuit are set in the host computer, and the PC host computer sends instructions to the FPGA to control the operation of each module. The host computer communicates with the FPGA through the serial port RS232 to achieve switch control of the laser diode, laser output power setting, working mode setting, output setting, pulse repetition frequency setting, and pulse width setting.

[0053] A laser diode driving method based on the above-mentioned high-speed semiconductor laser diode driving circuit system specifically comprises:

[0054] 1) Select the working mode: The host computer sends instructions to the FPGA, and the FPGA controls the working mode of the system. The working modes include pulse mode and continuous mode.

[0055] 2) Output RF drive signal: When in pulse mode, the trigger signal after passing through the internal and external trigger signal selection circuit module is sent to the narrow pulse signal generating circuit module, the narrow pulse signal generating circuit module converts the trigger signal into a pulse signal and sends it to the LD drive gain adjustment module, the LD drive gain adjustment module converts the input signal into a laser diode drive signal to drive the laser diode to work; when in continuous mode, the FPGA controls the constant current compensation circuit module to directly modulate the laser diode to keep the output optical power of the laser diode constant.

[0056] 3) Temperature control: While the working mode is selected in 1), the temperature control module controls the temperature of the laser diode so that the laser diode works at a constant temperature to ensure the stability of its optical power and wavelength.

[0057] 4) Constant current compensation: While the working mode is selected in 1), the constant current compensation circuit module controls the compensation current to make the laser diode output a constant current.

[0058] When the present invention starts working, the temperature control module uses a negative feedback closed-loop control system to control the TEC cooling or heating in the laser diode to reach and maintain the set temperature value, so that the laser works at a constant temperature, thereby ensuring the stability of the laser tube output. In the narrow pulse signal generation circuit module, the input trigger signal passes through the high-speed fan-out buffer, the delay chip, the high-speed logic gate chip and the high-speed comparator chip to generate the required narrow pulse signal; the high-speed fan-out buffer, the delay chip and the high-speed logic gate chip use full-range DC coupling, which reduces the complexity of the circuit and avoids the influence of phase offset during AC coupling, so that the drive signal amplitude and pulse width remain unchanged, ensuring the stability of the electrical signal input to the laser tube, and playing a decisive role in the stability of the output laser. The LD drive gain adjustment module adjusts the input reference voltage by setting the value of the upper computer to change the modulation current size, so that the laser diode can output stably and accurately. The present invention can work in pulse mode or continuous mode. In pulse mode, it can output 50ps-3ns narrow pulse laser; in continuous mode, it can output 1mW-10mW stable continuous laser. It has a wide range of applications, simple operation and convenient use.

[0059] After the present invention is successfully built, the test results are as follows: in the internal trigger mode, the operating frequency is adjustable within 10kHz-50MHz, in the external trigger mode, the operating frequency can reach 1GHz, in the pulse mode, the output laser pulse width is as low as 50ps, and in the continuous mode, the laser output power is stable and does not change with temperature. Compared with the existing laser diodes, this system has the following advantages: adjustable continuous / pulse mode, adjustable pulse frequency, memory storage of multiple modes, miniaturization, high integration, narrow output pulse, stable output power, simple operation, communication with the PC host computer through the USB interface, flexible use, and the output optical power and pulse width can be changed according to actual use requirements.

[0060] In summary, the high-speed semiconductor laser diode in the present invention has stable output power, can make the laser diode work in a stable temperature environment, and can switch between internal triggering / external triggering, continuous / pulse modes, and realizes the functions of adjustable pulse repetition frequency and pulse width. It is simple to operate and flexible to use, and can be applied to a variety of working scenarios.

[0061] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, all equivalent changes made according to the shape, structure and principle of the present invention without departing from the content of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-speed semiconductor laser diode drive circuit system, characterized in that: It includes FPGA, EEPROM, internal and external trigger signal selection circuit module, narrow pulse signal generation circuit module, constant current compensation circuit module, LD drive gain adjustment module and temperature control module; The FPGA is electrically connected to the EEPROM, the internal and external trigger signal selection circuit module, the narrow pulse signal generation circuit module, the constant current compensation circuit module and the LD drive gain adjustment module respectively; The LD drive gain adjustment module, the constant current compensation circuit module and the temperature control module are all electrically connected to the laser diode; The internal and external trigger signal selection circuit module is used to select the external or internal input trigger signal to adjust the working mode of the system; The narrow pulse signal generating circuit module is used to convert the trigger signal into a pulse signal; The temperature control module monitors and controls the operating temperature of the laser diode, so that the laser diode operates at a constant temperature.

2. A high-speed semiconductor laser diode driving circuit system as claimed in claim 1, characterized in that: The internal and external trigger signal selection circuit module includes a comparator and a selector electrically connected in sequence; The comparator is used to convert the external input signal into a trigger signal; The selector is electrically connected to the FPGA, and the FPGA generates a signal and sends it to the selection input terminal and the differential input terminal of the selector; When the FPGA sends a low-level signal to the selection input terminal of the selector, the internal and external trigger signal selection circuit module selects the external input signal, and the system is in external trigger mode at this time; When the FPGA sends a high-level signal to the selection input terminal of the selector, the internal and external trigger signal selection circuit module selects the internal input signal generated by the FPGA. At this time, the system is in internal trigger mode.

3. A high-speed semiconductor laser diode driving circuit system as claimed in claim 1, characterized in that: The narrow pulse signal generating circuit module comprises a high-speed fan-out buffer, a delay chip, a high-speed logic gate chip and a high-speed comparator which are electrically connected in sequence; The high-speed fan-out buffer, the delay chip, the high-speed logic gate chip and the high-speed comparator are DC-coupled in sequence; The high-speed fan-out buffer is used to divide an input trigger signal into four electrical signals with the same amplitude, one of which is output as a synchronization signal and two are output to the delay chip; The delay chip is used to set different delay values ​​for the two input signals and output them to the high-speed logic chip; The high-speed logic gate chip is used to set logic operations for the two input signals respectively; The high-speed comparator is used to eliminate noise in the electrical pulse signal and convert the signal output by the high-speed logic gate chip into an input signal for the driver chip; The pulse signal after noise filtering is sent to the LD drive gain adjustment module.

4. A high-speed semiconductor laser diode driving circuit system as claimed in claim 1, characterized in that: The LD driving gain adjustment module includes a digital-to-analog conversion chip and a driving chip which are electrically connected; The digital-to-analog conversion chip is electrically connected to the FPGA, and the digital-to-analog conversion chip adjusts the input reference voltage to control the modulation current of the driving chip; The driving chip converts the signal after the logic operation into a radio frequency driving signal and outputs it to the laser diode.

5. A high-speed semiconductor laser diode driving circuit system as claimed in claim 1, characterized in that: The temperature control module controls the TEC built into the laser diode to cool or heat the laser diode according to the preset operating temperature value of the laser diode, so that the laser diode operates at a constant temperature.

6. A high-speed semiconductor laser diode driving circuit system as claimed in claim 1, characterized in that: It also includes a host computer, which is electrically connected to the FPGA, and in which the electrical pulse width, working mode, gain voltage and trigger mode are set.

7. A laser diode driving method based on the high-speed semiconductor laser diode driving circuit system according to any one of claims 1 to 6, characterized in that: include: Select working mode: The host computer sends instructions to the FPGA, and the FPGA controls the working mode of the system. The working modes include pulse mode and continuous mode. Output RF drive signal: When in pulse mode, the trigger signal after passing through the internal and external trigger signal selection circuit module is sent to the narrow pulse signal generation circuit module, the narrow pulse signal generation circuit module converts the trigger signal into a pulse signal and sends it to the LD drive gain adjustment module, the LD drive gain adjustment module converts the input signal into a drive signal of the laser diode to drive the operation of the laser diode; When in continuous mode, the FPGA controls the constant current compensation circuit module to directly modulate the laser diode to keep the output optical power of the laser diode constant; Temperature control: The temperature control module controls the temperature of the laser diode, so that the laser diode works at a constant temperature to ensure the stability of its optical power and wavelength; Constant current compensation: The constant current compensation circuit module controls the compensation current to make the laser diode output a constant current.

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